Particulates in domestic premises. II. Ambient levels and indoor-outdoor relationships.

Three indoor environments, two residential and on institutional, were monitored for particulate and gaseous air pollutants over a one-year period. Inside air particulate levels decreased at night and under conditions of no household activity. Different homes showed different time lags in correlating inside vs outside particle counts. Indoor particle count reduction correlated to rate of air flow through the precipitator. The standard, portable household vacuum cleaner produced about a 100% increase in counts of particles measuring 1.0 mum and larger, as compared to a 50% increase produced by the central vacuum system. Particulates that were smaller than 1.0 mum were not substantially affected by smoking. The indoor gaseous pollutants showed very low maximum levels.